Question: 3 glue sticks cost $2.91. Which equation would help determine the cost of 2 glue sticks?
Explanation: There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 3 glue sticks. We want to know the cost of 2 glue sticks. We can write the numbers of glue sticks as a proportion: $\dfrac{3}{2}$ We know 3 glue sticks costs $2.91. We can let $x$ represent the unknown cost of 2 glue sticks. The proportion of these costs can be expressed as: $\dfrac{\$2.91}{x}$ The cost changes along with the number of glue sticks purchased, and so the two proportions are equivalent. $\dfrac{3}{2} = \dfrac{\$2.91}{x}$